1. Field of Invention
The present invention relates to an anti-deforming means for a steerer tube and more particularly, to an anti-deforming means disposed in the steerer tube to which a handlebar stem is securely engaged.
2. Related Prior Art
Referring to FIGS. 1 and 2, there is a kind of handlebar stem 80 having a vertical portion 81 and an inclined portion 82 extending from the vertical portion 81, the vertical portion 81 has a slit 801 longitudinally defined in a periphery thereof, each of the two opposite sides defining the slit 801 of the vertical portion 81 has two lugs 83 extending radially therefrom and each lug 83 has a hole defined therein such that the vertical portion 81 is securely mounted to a steerer tube 70 by engaging the corresponding pair of lugs 83 respectively extending from the two opposite sides defining the slit 801 by a bolt 84 and a nut (not shown). However, the steerer tube 70 securely engaged by the vertical portion 81 of the handlebar may be deformed inwardly because the steerer tube 70 is only a thin tube and is not allowed to increase its thickness in order to maintain an important character of lightness. Therefore, an anti-deforming means is employed to be disposed in the steerer tube 70, which includes an expander 90, a cap 94 and a driving element 93, the expander 90 has a tubular portion 901 through which a threaded hole 902 is centrally defined and two skirt portions 903 extending inclinedly and upwardly from an outer periphery of the tubular portion 901. The cap 94 has the same outer diameter as the steerer tube 70 so as to be put on a top of the steerer tube 70 and has a hole 941 defined in a center thereof. The driving element 93 includes a head 931 having the same outer diameter as the vertical portion 81 and a threaded rod 932 extending from an under side of the head 931 such that the threaded rod 932 passes through the hole 941 and threadedly engaged to the tubular portion 901 of the expander 90 received in the steerer tube 70, the two skirt portions 903 therefore respectively engages to an inner periphery of the steerer tube 70 and to provide an outward and radial force to the steerer tube 70 to prevent the steerer tube 70 from being deformed. However, such a skirt portion 903 provides only a limited support because of its thin-blade type and limited contact area between the skirt portion 903 and the steerer tube 70.
The present invention intends to provide an anti-deforming means which provides a firmly support to the steerer tube to mitigate and/or obviate the above-mentioned problems.